Cold blue for rust protection
 

After my brain-fart of knocking my Sherline off the bench a couple of weeks ago, and mostly repairing the aftermath of said boo-boo - I was left with several steel parts that now have scars on surfaces that were previously blackened.

I have seen several people that use a cold bluing solution for rust protection on jigs and tooling that they have made, so I decided to give it a try. Brownells was one of several solutions that I had seen used, so I ordered a small 4 ounce bottle of it.

Never having used this stuff before I wanted to see how well it worked, so I tried it on the top die that I made to press 2mm U-bolts. That die was milled out of a piece of 1/4"x3/4" hot rolled flat bar, so no harm-no foul if it turned out like crap. However I was impressed, it turned a nice deep black. And, considering that the only prep work it got was being wiped off with a paper towel the surface color is remarkably consistent. The next part that I cold blue will be properly cleaned before bluing. Any tooling that I make from now on will also get this cold bluing treatment.

Don

Re: Cold blue for rust protection
 

I've always had pretty good luck with Brownells working on guns over the years. As you noted, it's pretty easy to use and does provide pretty good rust protection. It will never equal true hot blueing as to color but for a beater it's ok. Little wipe down with oil once in a while and your good to go.

Re: Cold blue for rust protection
 

I've had good luck with Birchwood-Casey, hadn't tried Brownells.

I do know that when possible, Cold blue does like parts to be heated some before application. Also after bluing and cleaning to neutralize the salts, some more heat and soak in oil bath can really ramp up the corrosion protection.